A recently characterized virus, designated as BIV, is an infectious lentivirus that causes lymphadenopathy, lymphocytosis, central nervous system lesions, progressive weakness, and emaciation (Van Der Maaten et al, 1972. J. Natl. Cancer Inst. 49:1649-1657). Preliminary epidemiologic evidence suggests that BIV infection is widespread in cattle populations in the U.S. BIV has the morphology of a lentivirus, encodes a reverse transcriptase (RT) with a Mg.sup.2+ cation preference, and has immunologic cross-reactivity with HIV, SIV, and EIAV (Gonda et al, 1987, Nature 330:388-391). Moreover, the detection of sequence homology in the highly conserved RT domain of pol conclusively demonstrates that BIV Is a lentivirus, distinct from all previously characterized lentivirus isolates (Gonda et al, supra).
Non-functional clones of BIV have been prepared (Gonda et al, supra). The reasons for lack of biological activity in these clones are not fully understood.